Media feeding management

ABSTRACT

The present invention relates to an apparatus, system and method for managing media throughput in a printing device that may incorporate a sensing device. The gaps between feeding successive sheets of media may be controlled. The printing device may operate using different feeding modes having different gaps between the sheets of media.

FIELD OF INVENTION

The present invention relates to an apparatus, system and method for managing media feeding in printing devices.

BACKGROUND

Faster feeding of sheets of media from a stack of sheets will increase the throughput of a printer. Therefore, it is desired to maximize the throughput of a printer by feeding sheets from the stack of sheets at the fastest rate possible. When feeding sheets from a stack of sheets to a processing station in a printing device, it may be desired to feed the sheets as quickly as possible without a paper jam. To prevent a paper jam it may be useful to prevent the sheets from overlapping. Thus a minimum gap may be maintained between adjacent sheets being fed to prevent the sheets from overlapping while maintaining a desired feed rate.

There are times, however, when paper may jam in the printer for various reasons such as slippage of the feed rollers on the media. The slippage may be caused, for example, by use of media with a smoother surface than anticipated. The slippage may cause multiple sheets to stop in the paper path. The user may then need to clear the paper path with risk of damage to the printer or risk pieces of the media remaining in delicate areas of the printer, which may cause future failures.

SUMMARY

The present invention relates to a method or apparatus that may control a gap time interval between feeding of sheets of media in a printing device that may include a sensor and feeding according to a first feeding mode. The first feeding mode may comprise measuring a page length time (PL_(m)) for one or more page lengths to pass the sensor. The gap time period may also be controlled during feeding sheets of media based upon the measured page length time. The first feeding mode may also comprise measuring a feed time (FTm) for one or more pages passing the sensor. The gap period may also be controlled during feeding sheets of media based upon the measured feed time. The method or apparatus may also include a second feeding mode. The second feeding mode may delay feeding a subsequent sheet of media until a prior sheet of media clears the sensor. The method or apparatus may also adapt and change between the first and second feeding modes.

BRIEF DESCRIPTION OF DRAWINGS

Features and advantages of the present invention are set forth herein by description of embodiments consistent with the present invention, which description should be considered in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side view of an exemplary embodiment of a printing device illustrating an electrophotographic device.

FIG. 2 is a top view of an exemplary embodiment of a media feed tray.

FIG. 3 is a side view of an exemplary embodiment of a media feed tray.

FIG. 4 is an exemplary embodiment of a timing diagram relating to sensor state.

FIG. 5 is an exemplary embodiment of a timing diagram relating to gap and pick delay.

FIG. 6 is an exemplary embodiment of the present invention illustrating a method for “page length” mode.

FIG. 7 is an exemplary embodiment of the present invention illustrating a method for “feed time” mode.

FIG. 8 is an exemplary embodiment of the present invention illustrating a method for “consistent” mode.

FIGS. 9 and 10 are an exemplary embodiment of the present invention illustrating adaptation.

FIGS. 11 and 12 are an exemplary embodiment of the present invention illustrating another form of adaptation.

FIG. 13 is an illustration of an embodiment of the present invention relating to an article of machine readable media in relation to a processor and a user interface.

DETAILED DESCRIPTION

The present invention relates to the management of feeding media in a printing device. A printing device may be any device which creates images, such as text, characters or graphics, on media. Accordingly, a printing device may be an inkjet printer, an electrophotographic printer, a copier, a fax, an all-in-one device, or a multifunctional device.

An exemplary embodiment of a printing device may be an electrophotographic printer, illustrated in FIG. 1. Accordingly, the following describes an electrophotographic printer that may be suitable for use in the present invention.

The optical device 1 may project a light image onto a photosensitive drum 7 by projecting light on the basis of image information read from an external apparatus or the like. As shown in FIG. 1, a laser diode 1 b, a polygon mirror 1 c, a scanner motor 1 d, and an image-forming lens 1 e may be housed inside an optical unit 1 of the main body 14 of the apparatus. When, for example, an image signal may be supplied from an external apparatus, such as a computer, word processor or imaging device, to the printer or to a microprocessor 16 within the printer, the laser diode 1 b may emit light in response to the image signal, and projects the light onto the polygon mirror 1 c as image light. Polygon mirror 1 c may be rotated at high speed by the scanner motor 1 d. The image light reflected by the polygon mirror 1 c may be projected onto the photosensitive drum 7 via the image-forming lens 1 e and reflecting mirror 1 f. The surface of the photosensitive drum 7 may thus be selectively exposed to form a latent image corresponding to the image information.

The feeding device 3 for feeding the recording medium 2 (e.g., recording paper, cardstock, OHP sheet, envelopes, cloth, thin plate, etc.) may include the following components. A loading portion of a cassette 3 a may be provided in the inner bottom portion of the main body 14 of the apparatus. Upon the input of an image formation start signal, the recording media 2 within the cassette 3 a may be fed one-by-one from the top of the stack by a pickup roller 3 b, feeding rollers 3 c and follower rollers 3 d, pressed against the feeding roller 3 c.

A sheet of recording medium 2 may be fed to the nip portion between the photosensitive drum 7 and the transfer device 4 in synchronization with the performing of the image-formation operation described above, transferring the image to the recording medium. The recording medium 2 onto which a developed image has been transferred may be fed to the fixing device 5 and then ejected onto the ejection tray 6 by a pair of intermediate ejection rollers 3 e and a pair of ejection rollers 3 f. A pair of guide members 3 g for guiding the feeding of the recording medium 2 may be provided between each of the above-mentioned pairs of rollers.

The transfer device 4 transfers the developed latent image or toner image formed on the photosensitive drum 7 in the image-forming section onto the recording medium 2. The transfer device 4 consists of the transfer roller 4 as shown in FIG. 1. That is, the recording medium 2 may be pressed by the transfer roller 4 against the photosensitive drum 7 of the loaded process cartridge B. A voltage having a polarity opposite that of the latent image formed on the photosensitive drum 7 may be applied to the transfer roller 4 so that the developing agent on the photosensitive drum 7 may be transferred to the recording medium 2.

The fixing device 5 may fix the developing agent image transferred to the recording medium 2 by applying heat and pressure to the recording medium 2 carrying the toner image. As shown in FIG. 1, the fixing device 5 may comprise a driving rotating roller 5 a having a heater 5 b therein, and a fixing (pressure) roller 5 c, rotating in a driven manner in pressed contact with the drive roller 5 a. More specifically, when the recording medium 2 to which the developing agent image has been transferred moves between drive roller 5 a and fixing roller 5 c, heat may be applied by the heater located in the driving rotating roller 5 a and pressure may be applied to the recording medium by the fixing roller 5 c, thereby causing the developing agent (which comprises a colorant and a thermoplastic component) on the recording medium 2 to melt and become fixed to the recording medium 2.

Furthermore, the microprocessor 16 may communicate with a computer, network, word processor or imaging device using a variety of communication protocols. The microprocessor 16 may also process data within the printer, including data related to sensors and computing algorithms.

A process cartridge loading device by which the process cartridge B may be loaded into the image forming apparatus may be disposed within the apparatus A. Loading and unloading of the process cartridge B to and from the main body 14 of the apparatus may be performed by opening an open/close cover 15. Open/Close cover 15 may be provided with a conventional hinge (not shown) so that it can be opened or closed, and is mounted in the upper portion of the main body 14 of the apparatus. Opening the open/close cover 15 may reveal a cartridge loading space provided inside the main body 14 of the apparatus and may include conventional left and right guide members (not shown) mounted on the left and right inner-wall surfaces of the main body 14. Each of these guide members may be provided with a guide for inserting the process cartridge or developing agent assembly B. The process cartridge or assembly B may be inserted into and along the guides, and by closing the open/close cover 15. Furthermore, the open/close cover 15 may be provided in communication with a sensor (not illustrated), which may be triggered by opening or closing said cover 15.

The process cartridge or assembly B may comprise an image carrier and at least one process means. The process device may include a charging device for charging the surface of the image carrier, a developing device for forming a toner image on the image carrier, a cleaning device for cleaning the toner remaining on the surface of the image carrier, and the like. In the process cartridge B as shown is the charging device 8, the exposure section 9, the developing device 10, and the cleaning device 11 may be arranged around a photosensitive drum 7, which is an image carrier. These elements may be housed within a frame member formed of the developing agent frame member 12 and the cleaning frame member 13 so that they may be formed into one unit, thus making it possible to load and unload the unit into and out of the main body 14 of the apparatus. The process cartridge B may include the following elements: the photosensitive drum 7, the charging device 8, the exposure section 9, the developing device 10 and the cleaning device 11. However, it should be appreciated that some of these devices, such as the charging device 8, may be otherwise arranged within the main body 14 of the printing device.

The photosensitive drum 7 may have an organic photosensitive layer coated onto the outer peripheral surface of a cylindrical drum base formed from aluminum. The photosensitive drum 7 may be rotatably mounted on a frame member of the cartridge and the driving force of a drive motor disposed in the main body 14 of the apparatus may be transmitted to a drum cap (not shown). As a result, the photosensitive drum 7 may be caused to rotate in the direction of the arrow.

The charging means 8 may be used to uniformly charge the surface of the photosensitive drum 7. Preferably, a so-called contact charging method in which the charging means 8 is mounted on frame member 12 may be used.

The charging means 8 may be brought into contact with the photosensitive drum 7 so that the charging means 8 contacts the photosensitive drum 7 during the image formation. A DC voltage may be applied to the charging means 8 and the surface of the photosensitive drum 7 may be uniformly charged.

An exposure section 9 exposes a light image projected from the optical means onto the surface of the photosensitive drum 7 uniformly charged by the charging roller 8 so that a latent image may be formed on the surface of the photosensitive drum 7. An opening 9 for guiding the light image onto the top surface of the photosensitive drum 7 may be provided to form the exposure section.

FIG. 2 illustrates a sheet support tray of the present invention that may contain a stack of sheets therein for advancement by a pick mechanism. A tray 210, which may be located inside of a printer 211, for example, may be used to support sheets of media, such as, but not limited to, paper, card stock, film, such as transparencies, or printer labels, in a stack.

At the front end 216 of the tray 210, there may be an inclined wall 217, inclined at an obtuse angle from a bottom wall 215. On the inclined wall 217 may be a number of ribs 218 on which the sheet stack may be engaged. A pick mechanism 220 may be used to advance the media from the tray 210. The pick mechanism 220 may include a pair of feed rollers 221 and 222, which are driven from a motor 223 through a gear train, (not illustrated).

Referring to FIG. 3, the motor 323 may be alternately turned off and on by a processor 324 as each of the sheets 312 may be advanced from the top of the stack 314 of the sheets. A sheet 312 may be advanced along the inclined wall 317 through a predetermined feed path 319 and into a processing station, (not illustrated,) of the printer 311 where the media is printed. Located along the media feed path 319 may be a sensor 325, which may be in communication with the microprocessor 324.

In order to feed the sheets properly, a gap G may be maintained between consecutive sheets, for example sheet n and sheet n+1, to prevent the sheets from jamming or feeding multiple sheets at the same time. The gap G may be the distance between the trailing edge of sheet n and the leading edge of sheet n+1. However, it may be advantageous to keep this gap as small as possible to minimize the amount of time required between feeding individual sheets and to maintain a desired throughput.

Accordingly, the present invention is directed to an apparatus, system and method that may provide a gap between the sheets of media 312 that may utilize a media detection or input sensor 325 located along the media feed path 319 within the printing device, illustrated in FIG. 3. When media 312 is fed and passes by the sensor 325, the sensor 325 may be activated. It should be appreciated that the sensor may be any device, such as proximity or optical device, which may be capable of detecting a sheet of media.

Illustrated in FIG. 4 is a timing diagram of an exemplary embodiment of the state of the sensor as media travels through the printer. When the media is picked, 410, the sensor may be in an inactive or deactivated state. The sensor may remain deactivated, for example, while the media is traveling to the sensor, 420. When the leading edge of the media passes the sensor, the sensor may be activated 430. The sensor may remain activated during the amount of time necessary for the trailing edge of the media to pass the sensor 440. Once the trailing edge of the media passes by the sensor, the sensor may be deactivated at 450.

In one embodiment of the present invention, a determination of the length of the sheet of media (PL_(m)) may be made by the printing device. This determination may be utilized when the length of a sheet of media (PL) is unknown, such as when media is fed from a multipurpose tray, when the printing device lacks the ability to sense the length of a sheet of media or when the user uses a different sized sheet of media than what is programmed into the printing device. By determining the length of the sheet of media, the time between feeding sheets may be controlled to maintain an appropriate gap between the pages and speed the media feeding process to obtained desired throughput times. This mode of operation may be referred to herein as the “page length” mode. The “page length” mode may therefore be accomplished by the following methodology.

When the sensor is activated, a signal may be sent to the microprocessor representing the amount of time necessary for the media to pass by the sensor. From a combination of this time period, illustrated in FIG. 4 at 440, and other known factors, such as the velocity at which the media travels, which may be determined by the motor speed, etc., a determination may be made defining the length of the sheet of media. The measured length of the sheet of media may then be used to determine how to pick subsequent sheets and to maintain a desired gap.

In an embodiment of the invention, illustrated in FIG. 5, it is first useful to point out that the time necessary to feed a full sheet length (PL_(m)) from the tray and maintain a desired gap (G) may be determined by measuring the time between the microprocessor (not illustrated) sending a pick signal to begin the sheet feeding process and the microprocessor receiving a signal from a sensor 525 that detects the leading edge of the sheet 530. It can be appreciated that the time necessary to feed a full sheet and maintain a gap may be based upon the distance of the predetermined media path 319 (see FIG. 3) and other constants (e.g. velocity).

The expected feed time (FT_(exp)) may be considered the amount of time necessary for the leading edge 530 of a sheet n to trigger sensor 525 after the picking process has been initiated by the pick signal. The pick delay (PD) may be considered the amount of time lapsed after the expected feed time (FT_(exp)) and prior to picking of the next sheet, sheet n+1. This relationship may be represented by the following equation: PD+FT _(exp) =PL _(m) +G. Thus, solving for PD, the pick delay may be determined by the following equation: PD=PL _(m) +G−FT _(exp).

An exemplary method for adjusting the gap according to media length is illustrated in FIG. 6. The printer may be turned on, or started from standby mode or power save mode, at 610. At 612, a print job may be generated. A determination may be made on whether a print job may be a multiple page print job at 614. If the print job is not a multiple page print job the page may be printed 616.

If the print job is a multiple page print job then sheet n is picked 618. When the leading edge of sheet n passes by the input sensor, the input sensor may be activated 620 and sends a signal to the microprocessor which starts a timing device such as internal clock (not illustrated) or maintains a pulse count, which may be based on the clock time of the microprocessor or a specific period of time chosen. Once the trailing edge of sheet n passes the input sensor, the sensor may be deactivated 622 and the next sheet of media, sheet n+1, may be picked at 624 and the input sensor may be activated at 626.

Once the sensor has been deactivated for sheet n at 622, the microprocessor, may then compute the length of the media (PL_(m)) from the amount of time necessary for the media to pass the sensor and, for example, the speed at which the media may be traveling determined from the pick motor. Using the relationships described herein, a pick delay may be set based upon the measured media length (PL_(m)) and a desired gap.

Accordingly, in an exemplary embodiment, the feed time may be measured for a sheet n. The expected feed time FT_(exp) for subsequent sheets, n+1, n+2, etc. may then be determined by the measured feed time FT_(m) for sheet n. The gap time G, may be a desired gap length that may be translated into a time factor based on the velocity of the paper moving through the printer. It should be appreciated that the gap distance may be shorter than the distance between the input sensor and the pick mechanism. Using these factors it may then be possible to set a pick delay PD for subsequent sheets which may be adjusted to control or minimize the gap. A subsequent sheet, sheet n+2, may be picked at 628 according to the selected pick delay.

When the trailing edge of sheet n+1 passes the sensor, the sensor may be deactivated 630. The sensor may then be activated again at 632 for sheet n+2. If sheet n+2 is the final sheet as illustrated at 634, then the sensor may be de-activated at 636 and process may end until another print job is generated at 612. If sheet n+2 is not the last sheet then a subsequent sheet, sheet n+3 may be picked 638 according to the determined pick delay and the sensor responds, at 630-632, until a final page is reached at 634.

It should be appreciated that once the pick delay is identified which would allow one to control the gap time G, which should be understood as either maintaining a constant gap time or increasing the gap time or reducing the gap time, the implementation of a desired pick delay can be applied at any point in time. In addition, while the pick delay PD may be identified after the first sheet of media is picked, it can also be appreciated that the pick delay PD may be identified using any sheet media that may be fed to the printer. In this manner the system may allow the printer to control or minimize a gap depending upon, e.g. the size of a print job.

In another embodiment the gap may be controlled or minimized based on the measured feed time (FTm) of one or more sheets of media, referred to herein as “feed time” mode. As alluded to above, the feed time (FTm) of a sheet of media may be considered the amount of time between when a pick signal is issued by the processor and when the leading edge of a sheet of media reaches the sensor, wherein the sensor may be activated. Accordingly, the measured feed time (FI m) for a sheet n, may be used as the expected feed time (FTexp) for a subsequent, such as sheet n+1.

Using the relationship PD=PL+G−FT _(exp) an appropriate pick delay (PD) may be calculated by supplying a page length (PL) and desired gap (G) to the processor. The pick delay may be optimized for either maintaining a consistent throughput of media through the printing device or maintaining a consistent gap. This page length may be a page length determined from tray settings and/or user settings. The desired gap may be a set number for all media or a number determined for media type. The desired gap may also be set by the processor, or another device communicating with the processor.

Additionally, a factor of time HB may be added to the feed time expected to adjust the pick delay. This factor of time HB may be a desired preset number or a processor pulse or multiple processor pulses. For example, the factor of time may be any amount of time between 1 millisecond to 50 milliseconds and any increment therebetween, including 10 milliseconds, 11 milliseconds, 22 milliseconds, etc.

Furthermore, the measured feed time FTm may be compared to a maximum feed time FTmax. The FTmax may be set at a desired maximum feed time. For example, the maximum feed time may be the amount of time it may take to feed the last sheet of media from a media stack in a specific tray or it may be the amount of time necessary to feed a page length (PL). Accordingly, if the measured feed time FTm for sheet n+1 is greater than the maximum feed time FTmax then the feed time expected for a subsequent sheet FTexp_((n+2)) may again be set at the expected feed time for a previous sheet, such as FTexp_((n+1)).

An exemplary embodiment of “feed time” mode is illustrated in FIG. 7. At 710 the power may be turned on to the printing device or the printing device may be in standby or power save mode. At 112 a print job may be generated. A pick signal may be issued at 714 and a determination may be made as to whether the sheet of media being printed is a first sheet of media at 716.

If the sheet is a first sheet n, then the sensor may be activated when the leading edge of the sheet reaches the sensor at 718 and the feed time may be measured FTm(n). The measured feed time FTm_((n)) may be set as the expected feed time for the next sheet of media FTexp_((n+1)) at 720. The value of the expected feed time for the next sheet of media FTexp_((n+1)) may then be used to calculate a pick delay (PD) according to the relationships described herein at 740.

If it is determined that the sheet is not a first sheet n, then the sensor may be deactivated by the trailing edge of a prior sheet n at 722. The sensor may then be activated when the leading edge of the sheet, sheet n+1, reaches the sensor at 724 and the feed time may be measured FTm_((n+1)). A determination may then be made as to whether the measured feed time for sheet n+1 FTm_((n+1)) may be greater than a maximum feed time FTmax at 726.

If the measured feed time for sheet n+1, FTm_((n+1)) is greater than a maximum feed time FTmax at 726, then the feed time expected for the next sheet sheet n+2, FTexp_((n+2)), may be set to the feed time expected for a previous sheet, such as FTexp_((n+1)), at 728. This value may then be used to calculate a pick delay for the next sheet, sheet n+2 at 740. It should be appreciated that the deactivation of the sensor between a pick signal and the activation of the sensor may not affect the measurement of the feed time. Furthermore, depending on the desired gap, it should also be appreciated that the sensor may be deactivated prior to the pick signal for a subsequent page being activated.

If the measured feed time for sheet n+1, FTm_((n+1)) is not greater than the maximum feed time FTmax, then a determination may be made at 730 of whether the measured feed time for sheet n+1, FTm_((n+1)) is less than the expected feed time for sheet n+1, FTexp_((n+1)). If the feed time measured for sheet n+1, FTm_((n+1)) is less than the expected feed time for sheet n+1, FTexp_((n+1)) then the measured feed time FTm_((n+1)) may be set as an expected feed time for the next sheet, sheet n+2, FTexp_((n+2)) at 732. This value FTexp_((n+2)) may then be used to determine the pick delay for the next sheet, sheet n+2 at 740.

If the measured feed time for sheet n+1, FTm_((n+1)) is not less than the expected feed time for sheet n+1, FTexp_((n+1)) at 730, then the feed time may be adjusted to pick the next sheet, sheet n+2, sooner at 734 by adding a factor HB to the feed time. Accordingly, the feed time expected for the next sheet, sheet n+2, FTexp_((n+2)) may be the expected feed time for the sheet n+1, FTexp_((n+1)) plus a factor HB, wherein FTexp_((n+2)) =FTexp_((n+1)) +HB. The value of the expected feed time for sheet n+2, FTexp_((n+2)) may then be used to determine the pick delay for sheet n+2 at 740.

After a pick delay has been determined for the next sheet at 740, it may be determined whether there is another sheet to be printed in the print job at 742. If there is another sheet to be printed in the print job, the next sheet may be picked at 714. If there is not another sheet to be printed, then the sensor may be deactivated by the trailing edge of the sheet at 744 and the printing device may wait for a new print job to be generated at 712.

It should be appreciated that the reference to a first sheet n, is merely an arbitrary reference to the first sheet and the above manipulation and setting of a pick delay may be initiated at any point in a multi-page print job. For example, “feed time” mode may be initiated at the first, fourth, twelfth or at any time or sheet within a print job. Furthermore, as disclosed herein, it should be understood that the reference to n, n+1, n+2, etc may increase by one for each of the sheets being fed thereafter.

In an alternative embodiment of the present invention, it may be necessary for the media to be fed in a manner that delays feeding until a prior sheet clears the sensor before feeding the subsequent sheet. Such embodiment may be used either alone or in combination with the “page length mode” or “feed time mode” discussed above. In such embodiment the printer may wait for a sheet of media to clear the sensor prior to picking the next sheet. This may provide improved gap management and may be invoked by the user upon recognition of a feeding problem with difficult to handle media (i.e., any media that may not properly or regularly engage with a pick mechanism). Such feeding mode may therefore be understood as an alternative feeding mode with a gap time that may be different (e.g., longer) than that gap time in the “page length” or “feed time” feeding modes.

Expanding upon the above, this alternative feeding mode may therefore be triggered when the user identifies to the system a media type that may be hard to feed. For example, any type of media that may be difficult to pick and which may not be readily or repeatedly engaged by feed roller 221 and 222 illustrated in FIG. 2. Accordingly, when the user identifies such information to the processor, the processor may check against a preprogrammed table of media, such as transparencies, labels, envelopes, glossy paper, etc. and may instruct the system not to minimize the gap but to maintain a relatively consistent or constant gap.

Alternatively, the user may themselves select a certain input print setting that similarly does not seek to control or minimize the gap. Furthermore, the printing device may select to not seek to control or minimize the gap when a print job is sourced from a particular feed source, such as a multi-purpose feed tray. These various modes may be understood herein as a “consistent” feed mode in the sense that the system may not seek to control or minimize the gap and the gap may remain constant.

An exemplary embodiment of this second feeding mode may be illustrated in FIG. 8. The printing device power may be turned on or the printer may be activated from standby or power save mode at 810. Then a print job may be generated 812. A determination may then be made as to whether the print job is a multi-page print job at 814. If the print job is not a multi-page print job, the sheet may be printed at 816.

If the print job is a multi-page print job a determination may be made as to whether the user has selected the consistent feed mode or if the printing device automatically set the consistent feed mode at 818. If consistent feed mode has not been selected then the printer may feed according another mode at 820, such as the “page length” mode described above, measuring the length of the first sheet of media as it passes through the printer, and illustrated in FIG. 6, or the “feed time” mode illustrated in FIG. 7.

If consistent feed mode has been selected then the printing device may pick the first sheet, sheet n, at 822. The input sensor may be activated at 824 when the leading edge of the sheet has passed the sensor. Once the trailing edge of the sheet has passed the sensor, the sensor may be deactivated at 826. The printing device may determine whether the page may be a final page at 828. If the page is a final page, then the printing device may wait for a new print job to be generated at 812. If the sheet is not the final page in the print job, then the next sheet, sheet n+1, may be picked at 830.

Accordingly, the subsequent sheet may not be picked until the trailing edge of the prior sheet has passed the sensor. In this manner the gap may not be controlled or minimized. While the pick delay (PD) may or may not be identified in consistent mode, it should be appreciated that the PD may (in the “consistent” mode) relate to the following: PD=PL+FT _(exp).

Note that the page length may or may not be a measured page length (PL_(m)) as in this mode it may not be necessary to measure the page length.

Furthermore, the printing device may adapt and switch between the “page length” mode (see FIG. 6) or the “consistent” mode (see FIG. 8). For example, when media feeding failures occur due to gap closure, i.e. there is no gap between the sheets or subsequent sheets have fed into the prior sheets, the printing device may adjust between modes. One exemplary embodiment of the adaptive method is illustrated in FIGS. 9 and 10.

In FIG. 9, the printing device may be turned on or activated from standby or power save mode at 910. A print job may then be generated at 912. It may then be determined whether the print job is a multi-page print job at 914. If the print job is not a multi-page print job then the page may be printed at 916.

When the print job is determined to be a multi-page print job at 914, sheet n may be picked at 918. The sensor may be activated by the leading edge of sheet n moving through the media path at 920. Once the trailing edge of sheet n has passed the sensor the sensor may be de-activated at 922 and the next sheet, sheet n+1 may be picked at 924. Accordingly, it may now be possible for an appropriate pick delay to be identified for a desired gap length.

Sheet n+1 may activate the sensor at 926 and sheet n+2 may be picked at 928 according to the calculated pick delay. At 930, the trailing edge of sheet n+1 passes the sensor and the sensor may be de-activated. Then the leading edge of sheet n+2 may pass the sensor at 932. A determination may be made as to whether sheet n+2 may be the final sheet at 934. If it is the final sheet then as the trailing edge of sheet n+2 passes the sensor, the sensor may be deactivated at 936 and the printing device may wait for the next print job at 912. If a determination is made that sheet n+2 may not be the final sheet at 934, then sheet n+3 may be picked at 938.

In an exemplary embodiment of adaptation, a determination may then be made as to whether the media sensor has been de-activated at 940 for sheet n+2, which determination may be based upon a selected period of time. It should be appreciated that the selected amount of time may be greater than the time for a page length to pass the sensor, PL. If the sensor has been de-activated then the process may continue from 930. If the sensor has not been de-activated, a possible feeding error may have occurred. For example, it may indicate in this exemplary embodiment that sheet n+3 may have been improperly fed and overlapped with sheet n+2. The sensor may then detect a trailing edge of sheet n+3 which improperly overlapped sheet n+2. At this point the system may decide to adapt the process at 960 to consistent mode and elect to print on sheet n+4 the print information that was intended for sheet n+3. The system may elect not to adapt and proceed to step 940.

FIG. 10 illustrates an exemplary embodiment after adaptation to consistent mode. At 1012, sheet n+4 may be picked, which may replace any sheets not properly printed. The input sensor may be activated by the leading edge of sheet n+3 at 1014. At 1016, the trailing edge of sheet n+4 may pass the sensor and the sensor may be de-activated. Then a determination may be made whether sheet n+4 is the final page in the print job at 1018, if so then the sensor may be de-activated at 936 and the printing device may wait for a new print job at 912 (illustrated on FIG. 9). If sheet n+4 is not the final sheet a next sheet may be picked, sheet n+5, at 1020. The process continues at until the final sheet has been picked. Accordingly, the pick delay may not be controlled or minimized.

It should be appreciated that the decision to adapt may be made at any time after sheet n+1 has been picked. Furthermore, it should be appreciated that mode adaptation described herein may occur after any given of number of undetected gaps, such as after the second undetected gap has been determined, the fifth undetected gap has been determined, the tenth undetected gap has been determined, etc.

One non-limiting example of the above may be considered as follows. One may send a four page print job to the printer. The first page may be picked and fed through the printer. The second page may be picked after the trailing edge of the first page may clear the sensor. The third page may be picked based upon the gap needed for fastest throughput (“page length” mode). However, the input may then not see a gap between the second and third page (staging problem). The printer may print the second page and continue to feed media in the media path until the sensor is cleared. Accordingly, the third page may be fed without being printed on.

The printer may at this point make a decision of whether to adapt feeding where picking and gap time may be determined by a leading edge and a trailing of edge of a sheet of media to pass the sensor prior to picking the next sheet (“consistent mode”). Regardless of whether this decision is made, the printer may pick another page so that the third page may be printed on the fourth sheet. If the printer has been adapted to consistent mode then the fourth page to be printed may be picked and printed after the trailing edge of the third page has cleared the input sensor. If the printer has not been adapted to consistent mode and remains in page length mode, then the fourth page may be picked based upon the gap needed for fastest throughput.

This sequence of events may provide that the finished output of sheets may have an extra blank page in the output bin due to the indicated staging problem. Therefore, the number of times that the system allows a staged sheet to occur before entering consistent mode may be varied.

In another exemplary embodiment of adaptation, the printing device may adapt from “feed time” mode to “consistent” mode, as illustrated in FIGS. 11 and 12. In FIG. 11 the printing device may be set to “feed time” mode. At 1110 the power may be turned on to the printing device or the printing device may be activated from standby or power save mode. At 1112 a print job may be generated. A pick signal may be issued at 1114 and a determination may be made as to whether the sheet of media being printed is a first sheet of media at 1116.

If the sheet is a first sheet n, then the sensor may be activated when the sheet reaches the sensor at 1118 and the feed time may be measured FTm(n). The measured feed time FTm_((n)) may be set as the expected feed time for the next sheet of media FTexp_((n+1)) at 1120. The value of the expected feed time for the next sheet of media FTexp_((n+1)) may then be used to calculated a pick delay (PD) according to the relationships described herein at 1140.

If it is determined that the sheet is not a first sheet n, then a determination may be made as to whether the sensor has been deactivated after a selected period of time for a prior sheet n at 1122. The selected period of time may be any desired time period. For example, the selected period of time may be a page length (PL). If the sensor has de-activated for the previous sheet, such as first sheet n at 1122, then the sensor may be activated when sheet n+1 reaches the sensor at 1128 and the feed time may be measured FTm_((n+1)).

A determination may then be made as to whether the measured feed time for sheet n+1 FTm_((n+1)) may be greater than a maximum feed time FTmax at 1130. If the measured feed time for sheet n+1, FTm_((n+1)) is greater than a maximum feed time FTmax at 1130, then the feed time expected for the next sheet sheet n+2, FTexp_((n+2)), may be set to the feed time expected for a previous sheet, such as FTexp_((n+1)), at 1132. This value may then be used to calculate a pick delay for the next sheet, sheet n+2 at 1140. It should be appreciated that the deactivation of the sensor between a pick signal and the activation of the sensor may not affect the measurement of the feed time. Furthermore, depending on the desired gap, it should also be appreciated that the sensor may be deactivated prior to the pick signal for a subsequent page being activated.

If the measured feed time for sheet n+1, FTm_((n+1)) is not greater than the maximum feed time FTmax, then a determination may be made at 1134 of whether the measured feed time for sheet n+1, FTm_((n+1)) is less than the expected feed time for sheet n+1, FTexp_((n+1)). If the feed time measured for sheet n+1, FTm_((n+1)) is less than the expected feed time for sheet n+1, FTexp_((n+1)) then the measured feed time FTm_((n+1)) may be set as an expected feed time for the next sheet, sheet n+2, FTexp_((n+2)) at 1136. This value FTexp_((n+) 2) may then be used to determine the pick delay for the next sheet, sheet n+2 at 1140.

If the measured feed time for sheet n+1, FTm_((n+1)) is not less than the expected feed time for sheet n+1, FTexp_((n+1)) at 1134, then the feed time may be adjusted to pick the next sheet, sheet n+2, sooner at 1138 by adding a factor HB to the feed time. Accordingly, the feed time expected for the next sheet, sheet n+2, FTexp_((n+2)) may be the expected feed time for the sheet n+1, FTexp_((n+1)) plus a factor HB, wherein FTexp_((n+2)) =FTexp_((n+1)) +HB. The value of the expected feed time for sheet n+2, FTexp_((n+2)) may then be used to determine the pick delay for sheet n+2 at 1140.

After a pick delay has been determined for the next sheet at 1140, it may be determined whether there is another sheet to be printed in the print job at 1142. If there is another sheet to be printed in the print job, the next sheet may be picked at 1114. If there is not another sheet to be printed, then the sensor may be deactivated at 1144 and the printing device may wait for a new print job to be generated at 1112.

If the sensor has not been deactivated after a selected period of time at 1122 then the media may be fed until the sensor deactivates at 1124. A decision may be made regarding whether the printing device should adapt feeding to another feeding mode, such as “consistent mode,” at 1126.

If a decision is not made to adapt at 1126, then a new pick signal may be issued and sheet n+2 may be picked. The information for sheet n+1 may then be printed on sheet n+2. If a decision is made to adapt at 1126, then the printing device may begin to feed in “consistent” mode illustrated in FIG. 12 following step E.

In FIG. 12, the decision has been made to adapt to consistent mode and sheet n+2 may be picked at 1210. The printing device may print on sheet n+2 the information that would have been printed on sheet n+1. The sensor may be activated at 1212 and then after sheet n+2 passes the sensor, the sensor may be deactivated at 1214. A determination at 1216 may be made as to whether a sheet n+2 was the final page in the print job. If sheet n+2 is not the final page sheet n+3 may be picked at 1218 and the input sensor may be activated at 1212. If sheet n+2 is the final sheet the flow diagram may continue at F in FIG. 11. The sensor may be deactivated at 1144 (referring to FIG. 11) and the printing device may wait for a new print job to be generated at 1112.

It should also be appreciated that the functionality described herein for the embodiments of the present invention may be implemented by using hardware, software, or a combination of hardware and software, either within the printing device or outside the printing device, as desired. If implemented by software, a processor and a machine readable medium are required. The processor may be of any type of processor capable of providing the speed and functionality required by the embodiments of the invention. Machine-readable memory includes any media capable of storing instructions adapted to be executed by a processor. Some examples of such memory include, but are not limited to, read-only memory (ROM), random-access memory (RAM), programmable ROM (PROM), erasable programmable ROM (EPROM), electronically erasable programmable ROM (EEPROM), dynamic RAM (DRAM), magnetic disk (e.g., floppy disk and hard drive), optical disk (e.g. CD-ROM), and any other device that can store digital information. The instructions may be stored on medium in either a compressed and/or encrypted format. Accordingly, in the broad context of the present invention, and with attention to FIG. 13, the printing device may contain a processor (1310) and machine readable media (1320) and user interface (1330). It should be appreciated that the user interface may be any interface that the user has with the printing device, or any device that may be in communication with the printing device in which the user may input into the printing device. Devices in communication with the printing device may include, but are not limited to, computers, cameras, storage media, scanners, or other devices.

The foregoing description is provided to illustrate and explain the present invention. However, the description hereinabove should not be considered to limit the scope of the invention set forth in the claims appended here to. 

1. A method to control a gap between feeding of sheets of media in a printing device including a sensor, wherein said printing device is capable of feeding according to either a first mode or a second mode, the first mode comprising selecting a first gap based upon a measured page length time (PL_(m)) for a sheet of media; the second mode comprising feeding successive sheets of media with a second gap that is different from said first gap.
 2. The method of claim 1 wherein said first mode further comprises: providing said sensor to detect a leading and trailing edge of media passing said sensor; identifying a page length time (PL_(m)) for a sheet of media based on said leading and trailing edge of media passing said sensor; measuring a page length time (PL_(m)) for one or more page lengths to pass said sensor; and selecting said gap during feeding subsequent sheets of media based upon said measured page length time (PL_(m)).
 3. The method of claim 1 wherein second mode further comprises: identifying a trailing edge of a sheet of media passing said sensor; and feeding a subsequent sheet of media when said trailing edge is identified.
 4. The method of claim 2 wherein said gap comprises a gap time interval which comprises the time between detection of a trailing edge of sheet of media and a leading edge of a subsequent sheet of media.
 5. The method of claim 1 wherein said device is capable of changing from feeding in said first mode to said second mode based upon information received from said sensor.
 6. The method of claim 1 wherein said device is capable of changing from said first mode to said second mode when said sensor fails to detect a trailing edge of media after a selected period of time.
 7. The method of claim 6 wherein said selected period of time exceeds the PL_(m) of a prior sheet of media.
 8. The method of claim 1 wherein said device is capable of changing from feeding in said first mode to said second mode based upon user input.
 9. The method of claim 1 wherein said printing device includes a processor and said processor is capable of changing from feeding in said first mode to said second mode.
 10. The method of claim 9 wherein said processor initiates said second feeding mode when said user identifies a type of media to said processor.
 11. The method of claim 9 wherein said processor initiates said second feeding mode when said user identifies a particular feed source.
 12. The method of claim 1 wherein said sensor fails to detect a gap between successive sheets of media n and n+1 and said device is capable of printing information scheduled for sheet n+1 on sheet n+2.
 13. A media feeding apparatus comprising: a sensor and a processor in communication with said sensor wherein said processor is configured to feed according to either a first mode or a second mode, wherein said processor is configured in said first mode to select a first gap based upon a measured page length time (PL_(m)) for a sheet of media; wherein said processor is configured in said second mode to select a second gap that is different than said first gap.
 14. The media feeding apparatus of claim 13 wherein said sensor is capable of detecting a leading and trailing edge of media passing said sensor; and said processor in said first feeding mode is further configured to identify a measured page length time (PL_(m)) for a sheet of media and select said gap during feeding between subsequent sheets of media based upon said measured page length time (PL_(m)).
 15. The media feeding apparatus of claim 13 wherein said processor in said second mode is further configured to: identify a trailing edge of a sheet of media passing said sensor; and feed a subsequent sheet of media when said trailing edge is identified.
 16. The media feeding apparatus of claim 13 wherein said processor is configured to change from feeding in said first mode to said second mode based upon information received from said sensor.
 17. The media feeding apparatus of claim 13 wherein said processor is configured to change from said first mode to said second mode when said sensor fails to detect a trailing edge of media after a selected period of time.
 18. The media feeding apparatus of claim 17 wherein said selected period of time exceeds the PL_(m) of a prior sheet of media.
 19. The media feeding apparatus of claim 13 wherein said processor is configured to change from feeding in said first mode to said second mode based upon user input.
 20. The media feeding apparatus of claim 13 wherein said processor is configured to change from feeding in said first mode to said second mode when said user identifies a type of media to said processor.
 21. The media feeding apparatus of claim 20 wherein said processor is configured to change from feeding in said first mode to said second mode when said user identifies a particular feed source.
 22. The media feeding apparatus of claim 13 wherein said sensor fails to detect a gap between successive sheets of media n and n+1 and said device is configured to print information scheduled for sheet n+1 on sheet n+2.
 23. An article comprising: a storage medium having stored thereon instructions when executed by a machine result in the following operations: feeding according to one of: a first feeding mode comprising selecting a first gap based upon a measured page length time (PL_(m)) for a sheet of media; a second feeding mode comprising feeding successive sheets of media with a second gap that is different from said first gap.
 24. The article of claim 23 wherein said instructions when executed by said machine result in the following additional operations when feeding in said first mode: identifying a page length time (PL_(m)) for a sheet of media based on said leading and trailing edge of media passing a sensor; measuring a page length time (PL_(m)) for one or more page lengths to pass said sensor; and selecting said gap during feeding subsequent sheets of media based upon said measured page length time (PL_(m)).
 25. The article of claim 23 wherein said instructions when executed by said machine result in the following operations when feeding in said second feeding mode: identifying a trailing edge of a sheet of media passing a sensor; and feeding a subsequent sheet of media when said trailing edge is identified.
 26. The article of claim 23 wherein said instructions when executed by said machine result in the following operations: changing from feeding in said first mode to said second mode based upon information received from said sensor.
 27. The article of claim 23 wherein said instructions when executed by said machine result in the following operations: changing from said first mode to said second mode when said sensor fails to detect a trailing edge of media after a selected period of time.
 28. The article of claim 27 wherein said instructions when executed by said machine result in the following: said selected period of time exceeds the PL_(m) of a prior sheet of media.
 29. The article of claim 23 wherein said instructions that when executed by said machine result in the following operations: changing from feeding in said first mode to said second mode based upon user input.
 30. The article of claim 23 wherein said instructions when executed by said machine result in the following operations: changing from feeding in said first mode to said second mode wherein said second feeding mode is initiated by a user identifying a type of media.
 31. The article of claim 23 wherein said instructions when executed by said machine result in the following operations: changing from feeding in said first mode to said second mode wherein said second mode is initiated by a user identifying a particular feed source.
 32. The article of claim 23 wherein said instructions when executed by said machine result in the following operations: printing information scheduled for sheet n+1 on sheet n+2 when a gap is not detected between successive sheets of media n and n+1 after a selected period of time.
 33. A media feeding apparatus comprising: a sensor and a processor in communication with said sensor wherein said processor is configured to feed according to a first mode or a second mode, wherein said processor is configured in said first mode to select a first gap based upon a measured feed time (FTm) for a sheet of media; wherein said processor is configured in said second mode to select a second gap that is different from said first gap.
 34. The media feeding apparatus of claim 33 wherein said sensor is capable of detecting a leading and trailing edge of media passing said sensor; and said processor in said first feeding mode is further configured to communicate with said sensor and configured to identify a measured feed time (FT_(m)) for a sheet of media and select said gap for a subsequent sheet of media based upon said measured feed time (FT_(m)).
 35. The media feeding apparatus of claim 33 wherein said processor in said second mode is further configured to: identify of a trailing edge of a sheet of media passing said sensor; and feed a subsequent sheet of media when said trailing edge is identified.
 36. The media feeding apparatus of claim 33 wherein said sensor fails to detect a gap between successive sheets of media n and n+1 and said device is configured to print information scheduled for sheet n+1 on sheet n+2. 